Rechargeable batteries are an important source of clean portable power in a wide variety of electrical applications, including automobiles, boats and electric vehicles. Lead-acid batteries are one form of rechargeable battery that are commonly used to start engines, propel electric vehicles, and to act as non-interruptible sources of back-up power when an external supply of electricity is interrupted. While not particularly energy efficient, because of the weight of lead in comparison to other metals, the technology of lead-acid batteries is mature and, as a result, they are cheap, reliable, and readily produced and thus, continue to constitute a substantial portion of the rechargeable batteries being produced today.
The ability of lead-acid batteries to deliver large amounts of electrical power is well known, particularly when associated with the starting and powering of motor vehicles. Likewise, the need to test and recharge these batteries and the problems associated therewith are also well known. A number of battery testers and chargers have thus been developed.
Most conventional battery chargers are equipped to provide multiple charging rates for charging different size batteries. The multiple charging rates are achieved by varying the charging voltage at the battery terminals, generally by changing the transformer primary/secondary winding ratio. An operator manually selects the rate at which the battery should be charged and also the duration of the charge cycle if the charger is equipped with a timer function. Most conventional chargers do not, however, have an option for selecting the type of battery to be charged (e.g., Gell Cell, Deep Cycle, Flooded Lead Acid, Spiral Wound, etc.) As a result, chargers are typically configured to work for many types of batteries but is not optimal for all or any of these types.
Many faults found in lead-acid batteries and other types of batteries are the result of poor recharging control in conventional chargers. For example, an operator may undercharge or overcharge the battery at a very high rate resulting in the deterioration of the battery. Overcharging a battery wastes energy, reduces the life of the battery, and may permanently damage the battery. In addition, overcharging can accelerate deterioration of the battery condition.
Another drawback of conventional chargers is that they do not provide a mechanism for testing the condition including, for instance, the state of charge of the battery prior to charging. Without testing, operators do not know the current state of charge in a battery, how long and at what rate a particular battery should be charged, whether it is safe to charge the battery, and whether the battery is capable of accepting a charge.
A need still exists therefore for a battery charger that provides optimal charging for different types of batteries, provides improved recharging control, and can test the battery to be charged to determine the condition of the battery before charging.